The present invention relates to high pressure fuel supply pumps for gasoline common rail injection systems.
Single piston, cam driven high pressure fuel pumps have become a common solution for generating high pressure fuel in common rail direct injection gasoline engines. It is known in the industry that the pump must incorporate an outlet check valve to prevent pressure bleed back from the rail while the pump is in the intake stroke cycle. It has become an industry requirement to incorporate a pressure relief valve within the pump to protect the entire high pressure system from an unexpected excess pressure caused by a system malfunction. In order to protect the rail and injectors, the pressure relief valve must be in hydraulic communication with the rail, i.e., in parallel with the pump flow. In order to make the parallel hydraulic communication, typical executions have located the outlet check valve and pressure relief valve as separate devices within the pump housing.